TC45 Hydraulic leak down

[J_J]

Hellow all,
I am having the same issue and I am pulling my hair out. I also have a TC45A with a 16la loader and 758C backhoe with 510 on hours meter. At the recommendation of a local NH dealer I replaced the main pump due to only having 500PSI at the diverter valve? In order to not contaminate or damage the new pump I drained and blew out all the oil from the lines and bleed all the cylinders to remove any perceived containments, and changed the hydraulic oil and filter. Giddy to have all back together and chomping at the bit to get some work done this weekend I started it at 9:30 Saturday night only to still have 500PSI: :mur:
I found this post last night (this morning) at 1AM, so I did some more research and thought that maybe it might be the pressure relief valve in the diverter. I added some washers to it to see if it would make a difference. Nope!
Any ideas?

Thanks for the help.

Which valve or was steering activated when you read the 500 psi?

 

[jinman]

Which valve or was steering activated when you read the 500 psi?

I think you are referring to which "relief" valve? Is that right J_J? The relief valve is in the diverter valve block on this tractor. Fluid from the hydraulic pump goes directly to the diverter block from the hydraulic pump. There, it is regulated by the pressure relief valve. Then, with the diverter set to the FEL position, the fluid leaves the diverter and is applied to the joystick dual valve. With the FEL at neutral, the flow leaves the power beyond port and returns to the output side of the diverter where it is routed to the rest of the system (3PH and remotes or backhoe). If the power beyond port plug is missing, it dumps straight to the reservoir and can only apply low pressure to the rest of the system. I think this is the 500 psi that is being read.

Since Pfloyd said his pressure was checked at the diverter, I know the only place to conveniently check that pressure is after the fluid returns from the joystick. The connection from the pump is not a convenient pressure check point due to the fact that it is a flange fitting with an o-ring. I'd bet money that the dealer checked the pressure as it came back from the joystick instead of the applied pressure directly from the pump. Of course, I don't know, but this just sounds too suspicious to not check out. It's also a easy check PFloyd can do without any gages.

Edit: I forgot to say that the steering is a separate pump and system that would have no effect on the main system pressure.

 

[Pfloyd#1]

Thanks for all the ribbing guys! It is nice to laugh in between the frustration and no my name is not Pink, it痴 Fuchsia!
But on a serious note, first off let me say that I am a bad writer at best and lacking detail in my first post.

What I should have done at first was bit the bullet and buy the service manual, which I have now acquired (knowledge is power)!

Jinman, you are right! The service tech tested the system at the open plug on the diverter valve which is labeled TANK (low pressure) in the manual. So when I attached my pressure gauge I got the same reading. Bought a new pump for being ignorant.
I will check that plug!

Tonight using the trouble shooting guide from the manual, I attached my gauge to the top line for the FEL and started to run the engine up to 2600RPM but I did not cap off the other end of the line and when I moved the joy stick I got a little wet! Stop! Reconnect the lines to fill the line with fluid again. Reattach the gauge and cap the other end, Starting again I got up to about 2000rpm and was reading zero at neutral and got 2000psi when I started moving the joy stick but I did not trust the connection of the gauge so I backed off and retightened all the connections. This time I ran the throttle up to 2600 and started to move the joy stick. Zero pressure? trying to lift the bucket, lower the bucket, actuating everything on the backhoe, nothing would move. Before I would have to get up around 2000rpm to move anything now zero pressure everywhere.

As first mentioned I was having a problem with the system bleeding down over time so I had pressure to all the attachment but recently after moving about 40 yards of dirt, I started having to rev the engine to lift the bucket where痴 before I could lift it at idle.

J J, When I drained the cylinders, I pressurized all of them with 80 pounds of air on both sides to test if the seals were leaking. Only the retracting side of the backhoe bucket and the FEL bucket cylinders leaked air all other seals held pressure. All lines are correct and have reset the QD痴

I have not touched the 3PT valve as arljbuilding has.

My setup for the backhoe is a line that is plumbed at the PB port on the bottom of the front remote valve, left side and returned directly to the sump.

The next logical step is to do a flow test but where can I rent, borough or buy one.
Is it possible that the oil pump broke? or my first thought was maybe the sump filter?
Thanks for the assist
Bill

 

[jinman]

Tonight using the trouble shooting guide from the manual, I attached my gauge to the top line for the FEL and started to run the engine up to 2600RPM but I did not cap off the other end of the line and when I moved the joy stick I got a little wet! Stop! Reconnect the lines to fill the line with fluid again. Reattach the gauge and cap the other end, Starting again I got up to about 2000rpm and was reading zero at neutral and got 2000psi when I started moving the joy stick but I did not trust the connection of the gauge so I backed off and retightened all the connections. This time I ran the throttle up to 2600 and started to move the joy stick. Zero pressure? trying to lift the bucket, lower the bucket, actuating everything on the backhoe, nothing would move. Before I would have to get up around 2000rpm to move anything now zero pressure everywhere. Bill

Bill, this is the most disturbing news to me because in your last post, you said you changed shims in the pressure relief valve. You must have done that with no pressure checking. Now while testing for pressure, you rev your engine and pressure suddenly drops to zero. UH OH! Was your relief valve set so high you just blew your pump seals? I don't know, but it sure seems like a suspicious chain of events. You better check your engine oil to make sure you aren't filling the engine with hydraulic fluid. When the pump's seals blow out, the pressurized hydraulic fluid goes out around the input shaft to the hydraulic pump and straight into the engine crankcase. I don't know if your seals are blown and I hope I'm wrong, but just sayin'. . . .:confused3:

I have to leave soon because I have a Dr. Appt this morning to get hearing aids fitted (getting old is the pits!). I'll be back this afternoon and be able to help you more with suggestions.

I can tell you that if you look at the face of the diverter valve, there is a book decal. Directly under that book decal is a movable slotted screw. Just to the right of it is a port with an allen head screw in it. That is the pressure test port that should be used if you want to read pressure directly at the diverter. The screw head should be slanted to the right so the slot is pointing to the 2 o'clock position while using this port for testing. Return the diverter to it's 10 o'clock position or whatever it was before when you are finished.

Now, you can also use your loader quick connect, but your description of leaks tells me you might not have a quick connect male adapter on your gage. I don't know how you had the gage plumbed in, but if read 2000 psi once, it surely should have done it again unless the gage failed. When you move the joystick, can you hear the engine load down any by the hydraulic pump?

 

[Pfloyd#1]

Jim,
I forgot to tell you that the shim that I had added I had removed so it was back to factory or the way it was. Checked the engine oil, all is good but will keep an eye on it.

The reason that I had pressure one minute and not the next is that you were right about the allen head plug, it had worked its way all the way out and was just laying sideways in the chamber. Reinstalled and all is normal. I did not do a pressure test but every thing seems to be working as before. Thanks for the assist.
One more question, is this a well known problem by New Holland?
Thanks again
Bill

P.S. J.J. On my two spool valve, which is different than the picture Jim has, the allen head plug is directly above the pressure inlet line on the right side of the valve so I am thinking that is why I did not have pressure to anything.
Thanks!

 

[jinman]

Bill, that is TERRIFIC news. I was really worried. What a great job you did of checking and finding the loose plug.:thumbsup:

About dealerships. . . I don't know what is up with your dealer. If I were you, I'd be pretty darn upset that they sold you a new pump when all you needed was a simple plug replaced. Yes, this happens often. I know about it due to all the instances I've seen here and the symptoms are always the same. TBN member RickB who is the Member of the Month for July was the first to make me aware of the plug. I had heard something about it, but he described the issue more clearly. He is a New Holland Senior Tech at a dealership in New York. You will have to decide for yourself, but it tells me that the service department at your dealer is not very savvy. I just think they went on an "easter egg hunt" on your tractor and you paid for it.

EDIT: I posted yesterday that I had a hearing appt. Well my hearing aids are terrific! The VA clinic fitted the hearing aids and they are barely visible. My wife had to look closely to even see them. I was shocked when I got into my car and turned on the key. I heard chimes for the first time ever since I bought the car in 2008. I now hear the full spectrum of sound and it is awesome!

 

[wdchyd]

Good job PFloyd.......:thumbsup:

 

[J_J]

Pfloyd#1

P.S. J.J. On my two spool valve, which is different than the picture Jim has, the allen head plug is directly above the pressure inlet line on the right side of the valve so I am thinking that is why I did not have pressure to anything.
Thanks!


Correct me if I am wrong, but the PB port which has the hex screw for PB, should be in the PB port which is usually on the tank side of the valve. If this is where you read the pressure, that would be logical. as the fluid was using two paths to get to the reservoir. I suspect that when you tried to use the 3pt, you blocked some of the fluid and it went to the tank via the tank port, and you had very little 3pt action. With the hex screw installed, and you put a gage at the PB port, you will read full system pressure if you are using the 3pt to raise a heavy load. With the 3pt in neutral, you would read very little pressure.
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